Okay, I have a DEC 3000 300X. It appears to work. But of course it's
designed to work with DEC keybaords and mice. There's nothing wrong
with this, except that I don't much like DEC keyboards and mice.
I'd like to connect up other devices - possibly a different keyboard,
possibly another machine's serial port doing appropriate reprocessing.
But for this I need to know the electrical interface specs. What
indications I have found indicate that the basic protocol is simple
4800-baud async serial, and I've found source code that describes the
protocol layered on top of that. What I haven't found is anything that
describes what's _below_ that: the connector pinout(s), whether the
interface is voltage-level or current-loop, what the voltages or
currents are, what sort of power (voltage and current capability) is
provided by the host, that sort of thing.
Anyone have this information for the keyboard/mouse port of a
3000-300X? Or know where I can find it? I did some searching but
turned up nothing of any use; perhaps I just never found the right
search terms.
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